It is an offense, to pollute the water with things like oil and garbage, fuel, antifreeze and other toxic substances such as cleaning supplies. Biodegradable cleaning supplies are recommended for on-water use. If you have accidentally polluted the water, or see evidence of someone doing so, report it immediately to a Government of Canada pollution prevention officer. Boaters should also be aware of the problem of carrying unwanted species from one area to another (cross-contamination). In some areas of Canada, vessels are prohibited from pumping sewage (also known as blackwater) overboard. When transporting a vessel from one body of water to another, clean the bottom and bilges to prevent spreading unwanted invasive species.